Declension table of ?hetavya

Neuter	Singular	Dual	Plural
Nominative	hetavyam	hetavye	hetavyāni
Vocative	hetavya	hetavye	hetavyāni
Accusative	hetavyam	hetavye	hetavyāni
Instrumental	hetavyena	hetavyābhyām	hetavyaiḥ
Dative	hetavyāya	hetavyābhyām	hetavyebhyaḥ
Ablative	hetavyāt	hetavyābhyām	hetavyebhyaḥ
Genitive	hetavyasya	hetavyayoḥ	hetavyānām
Locative	hetavye	hetavyayoḥ	hetavyeṣu

Compound hetavya -

Adverb -hetavyam -hetavyāt